database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-28 23:42:10 +03:00
Code Activity

Relax locking during GetCurrentVirtualXIDs(). Earlier improvements

Browse Source 
to handling of btree delete records mean that all snapshot
conflicts on standby now have a valid, useful latestRemovedXid.
Our earlier approach using LW_EXCLUSIVE was useful when we didnt
always have a valid value, though is no longer useful or necessary.
Asserts added to code path to prove and ensure this is the case.
This will reduce contention and improve performance of larger Hot
Standby servers.
This commit is contained in:
Simon Riggs
2010-04-21 19:08:14 +00:00
parent bc2b85d904
commit 0192abc4d7
2 changed files with 39 additions and 62 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
src/backend/storage/ipc/standby.c
View File

@ -11,7 +11,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/ipc/standby.c,v 1.16 2010/04/06 10:50:57 sriggs Exp $
* $PostgreSQL: pgsql/src/backend/storage/ipc/standby.c,v 1.17 2010/04/21 19:08:14 sriggs Exp $
*
*-------------------------------------------------------------------------
*/
@ -246,6 +246,24 @@ ResolveRecoveryConflictWithSnapshot(TransactionId latestRemovedXid, RelFileNode
{
VirtualTransactionId *backends;
/*
* If we get passed InvalidTransactionId then we are a little surprised,
* but it is theoretically possible, so spit out a LOG message, but not
* one that needs translating.
*
* We grab latestCompletedXid instead because this is the very latest
* value it could ever be.
*/
if (!TransactionIdIsValid(latestRemovedXid))
{
elog(LOG, "Invalid latestRemovedXid reported, using latestCompletedXid instead");
LWLockAcquire(ProcArrayLock, LW_SHARED);
latestRemovedXid = ShmemVariableCache->latestCompletedXid;
LWLockRelease(ProcArrayLock);
}
Assert(TransactionIdIsValid(latestRemovedXid));
backends = GetConflictingVirtualXIDs(latestRemovedXid,
node.dbNode);